In medical interventions on or in bodies of living beings in which one or more than one medical instrument is introduced at least partially into the body of the living being such that the instruments are at least partially no longer directly visible, increasing use is made of position detection systems, referred to as navigation and tracking systems, by means of which the positions of the instruments in the body of the living being are detected and can be superimposed on a 2D or 3D image of the inside of the body of the living being. The image of the inside of the living being's body is usually a preoperatively recorded X-ray, ultrasound or magnetic resonance image. The superimposing of the instrument or instruments on the image of the inside of the living being's body enables a physician performing the medical intervention to handle or navigate the instruments, which may be for example catheters, puncture needles, endoscopes, etc., with the aid of an image.
Examples that may be cited of position detection systems or navigation and tracking systems are the CAPPA system of the company CAS Innovations AG, the Polaris optical navigation and tracking system of the company Northern Digital as well as the Aurora electromagnetic navigation and tracking system of the company Northern Digital. By means of position detection systems or navigation and tracking systems of this kind the positions of instruments in the body of a living being can be determined and, as already mentioned, superimposed onto a 3D image or a 3D image dataset for example or correlated with the latter and visualized on a display unit.
A system for navigating a medical instrument in an operating region of a living being is described in US 2007/0270686 A1, wherein acceleration sensors associated with a navigation system are disposed in the distal end of the medical instrument in order to determine the current position of the medical instrument at any given time. Based on the determined position in each case, the medical instrument can be navigated in the body of the living being.
The post-published German patent application DE 10 2006 049 575 A1 discloses a detecting device for detecting an object in up to three dimensions by means of X-rays. The device additionally comprises a location sensor for determining the position of a medical instrument and a movement sensor, e.g. an accelerometer, by means of which a movement of a patient can be registered.
A device and a method for fusing image datasets are also known from DE 10 2005 037 426 A1. Movements of a patient can be registered with the aid of a movement sensor, e.g. an accelerometer, and taken into account during the image fusion.
However, involuntary movements of a living being, which are caused for example by the breathing and heartbeat of the living being, are problematic for the use of navigation and tracking systems during medical interventions. Thus, during a medical intervention in or on moving tissue of a living being, e.g. a moving organ of a living being, it is not only the target region or target tissue of the intervention that moves, but also the instrument used for the intervention, as a result of which the position determination or tracking of the used instrument, and consequently the navigation of the instrument, is rendered more difficult or, as the case may be, imprecise.